The present invention relates to a process for removing water-soluble organics from waste streams. In the first step, the organics-containing water is contacted with base to reduce the solubility of the dissolved organics. In the second step, the organics-containing water is contacted and thoroughly mixed with a free oil to coalesce the dissolved organics. In the third step, the free oil phase is separated from the aqueous phase to produce substantially organic-free produced water.
A variety of industrial processes generate aqueous waste streams containing contaminating amounts of organic compounds. Before such streams can be discharged into a receiving body of water, the organics content must be substantially reduced to meet state and federal regulatory standards.
For example in the manufacture of polyethyleneimine the process usually generates waste water streams. The water may contain significant amounts of dissolved sodium salts and other contaminating hydrocarbons. If not removed, these contaminants are measured as oil and grease when the water is acidified and freon extracted, pursuant to EPA gravimetric test methods. Thus, it is desirable to treat such water so that it can be discharged without violating regulatory standards.
Previous workers in the field attempted to remove dissolved organic contaminants by acidification. They believed that the dissolved organics would form a free oil phase at low pH's and could be removed by settling or flotation. For example, U.S. Pat. No. 4,401,570 discloses a method of removing organic esters from waste water using acidification. We have found, however, that these organics are too finely dispersed to allow them to settle or float. Thus, the organics remained and continued to result in unacceptable levels of oil and grease in the water stream.
Accordingly, it is the principle object of this invention to economically remove water-soluble organics from waste streams.